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50-100 ul Single breath

Figure 6 Pulmonary "solutions" landscape. Though a large number of solution inhalers are under development, none has yet made it to market. Nebulizers remain the only solution devices currently available.

Figure 7 Lung deposition for new inhalation technologies over the period 1980-2000. (From Refs. 7, 20, 27, 32-50.)

reported for a new technology. It can be seen that prior to 1995 the average delivery efficiency, i.e., the percentage of the nominal dose delivered to the lungs, for inhalation technologies was around 20%. After 1995 performance improved dramatically. The average deposition values reported in 2000 were around 4050%, with the highest value being 80%. The only conclusion that can be drawn from these numbers is that the patent activity, which began at the start of the 1990s (Fig. 2), has really led to product performance improvements. However, the reported data are, in general, produced with prototype devices and formulations. Because of the phase lag caused by the long development and registration time frames for pharmaceutical products, this tremendous improvement in product performance has not yet filtered through to market products. An example of this lag is obtained by comparing the patent-filing dates for the SMI technologies, the late 1980s and 1990s, to the publication of clinical data, 1995 onward. There are no SMI data in the early part of the decade of the 1990s.

However, one area where "new" products have made it to market, but where dramatic improvements have deliberately not been realized, is in the replacement HFA pMDIs. As already discussed, with the exception of two or three products, the regulatory and commercial pressures to replace the "old" CFC pMDIs with new HFA pMDIs with similar performance have resulted in possible product improvements that have not been implemented.

The other question that should perhaps be asked going forward is: Where and when do molecules need these improved delivery efficiencies? If local lung delivery is compared to other forms of drug delivery, in terms of the percentage of the nominal dose reaching the site of action, topical lung delivery is, and has always been, the most efficient delivery modality, and one has to ask why it needs improving. There are some obvious instances where it would be advantageous, for example, when oral or gastrointestinal exposure needs to be limited or avoided, where the drug is expensive, or where systemic delivery through the peripheral lung is required. Efficient second-generation pulmonary technologies are therefore here to stay, although they may not be necessary for all molecules.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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